Roll-over protection structure with deformable legs

ABSTRACT

A roll-over protection structure having spaced upright legs including relatively rigid upper end portions, relatively rigid lower end portions secured to a vehicle frame, and central portions of reduced cross sectional areas from the end portions to absorb energy and predictably deform during a vehicle rollover rather than having the legs fracture at their end portions to minimize the possibility of complete separation of the protection structure from the vehicle.

United States Patent Adams [75] Inventor: Stanely B. Adams, Yorkville,Ill. [73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: June 14, 1972 21 App1.No.: 262,552

[52] US. Cl. 280/150 C, 296/102 [51] Int. Cl B62d 25/06 [58] Field ofSearch 296/102; 280/150 C [56] References Cited UNITED STATES PATENTS3,527,474 9/1970 Boersma 296/102 3,656,803 4/1972 Brown 296/1023,578,377 5/1971 Babbitt 296/102 3,712,664 1/1973 May 296/102 [451 Feb.12, 1974 FOREIGN PATENTS OR APPLICATIONS 1,289,440 4/1966 Germany296/102 Primary ExaminerDavid Schonberg Assistant ExaminerReinhard .l.Eisenzopf Attorney, Agent, or F irm-Ralph E. Walters [5 7 ABSTRACT Aroll-over protection structure having spaced upright legs includingrelatively rigid upper end portions, relatively rigid lower end portionssecured to a vehicle frame, and central portions of reduced crosssectional areas from the end portions to absorb energy and predictablydeform during a vehicle roll-over rather than having the legs fractureat their end portions to minimize the possibility of completeseparationof the'protection structure from the vehicle.

5 Claims, 6 Drawing Figures PATENTED FEB 1 2 Sam 1 or 4 PAIENIEB FEB I 2I974 SHEU 2 BF 4 1 ROLL-OVER PROTECTION STRUCTURE WITH DEFORMABLE LEGSBACKGROUND OF THE INVENTION The present emphasis on operator safety hasled to an extensive development program for providing roll-overprotection structures on earthmoving vehicles. The most obvious approachwould be to fabricate a super strong, relatively rigid frame around theoperator. However, this is impractical from the standpoint of economics,space limitations on the vehicle, loss of visibility to the operator,changes to the center of gravity and the like. Other structures of theprior art have provided a plurality of substantially uniformlysectioned, rectangular or cylindrical posts which are weldably orotherwise integrally secured to each other above the operator station.While these relatively economical structures are intended to meet thenew Government standards, actual tests have shown such structuresgenerally fail by sudden fracture at the weld joints adjacent to theirextremities, resulting in complete separation of the protectionstructure from the vehicle or collapse of the structure on the vehicle.It is believed, therefore, that by controlling the cross section of thelegs of the roll-over protection structure, energy will be absorbed inthe legs through plastic deformation thereof in predetermined zonesleast subject to fracture to avoid complete separation of the structurefrom the vehicle or collapse of the structure on the vehicle.

SUMMARY AND OBJECTS OF THE INVENTION Accordingly, it is an object of thepresent invention to provide an improved roll-over protection structurefor earthmoving vehicles.

It is another object of the invention to provide such an improvedroll-over protection structure having legs which are predictablydeformable in specific zones during a vehicle roll-over.

It is another object to provide a roll-over protection structure of thecharacter described having legs providing weldably secured end portionsand centrally deformable center portions capable of relatively extensivedeformation prior to complete fracturing of the weldments at the endportions of the legs to minimize complete separation of the protectionstructure from the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of aroll-over protection structure embodying the principles of the presentinvention disposed on a wheel tractor.

FIG. 2 is a somewhat enlarged partial front elevational view of theright half of the roll-over protection structure as viewed in thedirection of the arrows on line II-II of FIG. 1.

FIG. 3 is a somewhat enlarged transverse horizontal cross sectional viewof the central portion of the leg of the roll-over protection structuretaken along the line III-III of FIG. 2.

FIG. 4 is a somewhat enlarged transverse horizontal cross sectional viewof a base portion of the leg of the roll-over protection structure takenalong the line lV-IV of FIG. 2.

FIG. 5 is a side elevational view of an alternate embodiment of theroll-over protection structure of the subject invention.

FIG. 6 is a front elevational view of the alternate embodiment of theroll-over protection structure of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT With particular reference toFIGS. 1 and 2, a rollover protection structure shown generally-at 10 isremovably secured through a pair of intermediate support brackets 12 toa relatively rigid pair of horizontally and generally longitudinalvehicle frame elements 14 disposed on either side of a vehicle 16. Whilethe vehicle is illustrated as an articulated wheeled earthmoving unit,it may be appreciated that the roll-over protective structure 10 can beadapted to virtually any type of earth traversing vehicle.

More specifically, the roll-over protection structure 10 includes a pairof substantially upright legs 18, only one of which is shown forillustrative convenience. Each of the legs is of slightly upwardlytapered form as shown by the side view of FIG. 1. Each of the legsincludes a relatively rigid base or lower end portion 20 having a flatmounting flange 22 which is disposed in facing engagement with apedestal plate 24 of the support bracket 12. A plurality of retainingbolts 26 rigidly secure the flange to the plate, and a similar series ofretaining bolts 28 attach a base plate 30 of the bracket to the vehicleframe 14.

Each of the legs 18 also has a deformable central portion as shown bythe reference numeral 32. The central portion of each leg is fabricatedin a substantially rectangular box section configuration as shown inFIG. 3. The leg includes a U-shaped outer plate 34 and an inner plate 36weldably secured thereto by a pair of longitudinally disposedsubstantially vertical welds 38.

Each leg 18 further includes a relatively rigid upper end portion 40which is integrally secured to a box-like cross frame or beam structureshown generally at 42. The transverse beam 42 includes a pair ofvertically arranged and longitudinally spaced cross plates 44, a lowerhorizontally disposed spanning plate 46, and an upper canopy plate 48which extends forwardly in overlying protective relation to an operationstation 50. For purposes of additional strength, a longitudinallyextending tapered angle member 52 is weldably secured to a dependingouter side surface 54 of the canopy plate 48 on each side of theprotective structure 10. Further, a pair of gussets 56 are weldablyattached to the angle members 52, the front cross plate 44, and thecover plate 48. An additional U-shaped channel 58 and a front crossplate 60 transversely strengthen the forward portion of the structure.

A transversely disposed box beam shown generally at 62 is weldably orotherwise rigidly secured in interconnecting relation between the lowerend portions 20 of the legs. The box beam includes a horizontallydisposed cover plate 64, a spaced base plate 66, and a pair ofvertically arranged front and rear plates 68. A plate 70, weldablyincorporated internally of each leg, is horizontally aligned with thecover plate 64 to provide a relatively rigid substructure.

As best shown in FIG. 2, an upper transition zone or hinge jointindicated generally at 72 is located between the upper end portion 40and the central portion 32 of the leg 18. A similar lower transitionzone or hinge joint identified at 74 is disposed between the baseportion 20 and the central portion of the leg. These upper and lowertransition zones substantially define plastically deformable hingejoints when the roll-over protection structure is subjected to a forceapplied laterally or transversely of the vehicle to the outside topmember 54 thereof as shown at F in FIG. 2. With such a loading, which isprojectionally equivalent to the shock loading imposed on the structuredue to a vehicle rollover, the legs 18 tend to be plastically deformedbetween the hinge joints 72 and 74.

Immediately above the hinge joint location 72 and below the hinge joint74, the increased transverse cross section provides a relatively morerigid structure which is only deformable in a generally elasticcondition. In other words, during a vehicle roll-over, the sturdiersections are not normally strained beyond their elastic limits. However,the transition zones or hinge joints 72 and 74 define zones which aresubject to potential strain beyond their elastic limits so that energyis absorbed therebetween through a controlled yielding action. Thetransition zones are tapered to provide a somewhat narrower transversewidth in the central portions 32 when compared with the upper endportions 40 and lower end portions 20 of the legs 18.

ALTERNATE EMBODIMENT While in the preferred embodiment of the roll-overprotection structure the legs 18 and the support brackets 12 are shownas separate components, these elements may be combined to achievesimilar operator protection. As bestshown in FIGS. and 6, a downwardlyextending leg structure 76 includes an integral base plate 78 on each ofthe legs. Each of the legs 76 is of rectangular fabrication including aninner side plate 80 and an outer side plate 82, as well as a front plate84 and a rear plate 86.

As shown in FIG. 6, each of the two leg structures 76 includes arelatively rigid upper end portion 92, a more flexible central portion94, and a relatively rigid base portion 96. Contributing to the strengthof the base portion of the legs is a substantially vertically orientedplate 98 and a pair of box-like beams 100 arranged to form a crossbracing integrally secured to the base portion 96. Above thissubstructure, the transverse cross section of each leg is decreased in apredetermined manner to form a pair of lower deformable hinge joints ortransition zones as shown generally at 102 and 104 in a mannercomparable to the transition zones of the preferred embodiment.Similarly, a pair of upper transition zones shown generally at 106 and108 define with the zones 102 and 104 the extremities of the pair ofcentral leg portions 94 of substantially uniform profile and with theindividual plates thereof integrally secured to each other by generallyvertically disposed welds.

An upper rear portion 110 of the alternate roll-over structure alsoincludes a transversely arranged, inverted U-shaped beam 112 and a pairof laterally spaced, forwardly extending bracing channels 114 whichsupport a protecting canopy 116. With a lateral load F applied to theupper part of the structure 76 as shown in FIG. 6, the structure isdeflected toward a phantom line position shown at 118. With anincreasing force, the material in the area of transition zones 102, 104,106, and 108, as well as the central portions 94 of both legs, passesbeyond the elastic limit to the plastic range where energy of a vehicleroll-over would normally be absorbed.

While the preferred and alternate embodiments of the roll-overprotection structure are shown with only two supporting legs, it will beappreciated that the number of legs is incidental to the basicprinciples set forth above. For example, four or six legs can also bedesigned with central portions thereof of reduced cross sectional areaso that in yielding, energy will be absorbed in a predetermined andcontrolled manner. It is further apparent that variations might bepossible that would fall within the scope of the present invention,which is not intended to be limited except as defined in the followingclaims.

What is claimed is:

1. A roll-over protection structure comprising;

a vehicle frame having an operators station thereon,

spaced upright leg means securable to said frame in upstanding relationfrom said operators station and having relatively rigid upper and lowerend portions, and l a deformable central portion providing a pair ofelevationally spaced upper and lower transition zones of substantiallyreduced cross sectional area from said upper and lower end portions withsaid zones being respectively disposed between said upper end portionand said central portion, and between said lower end portion and saidcentral portion so that when subjected to loading during a vehicleroll-over the central portion is effective to absorb energy andpredictably deform in locations spaced a predetermined distance fromsaid upper and lower end portions of said leg means and generallycontiguously associated with said upper and lower transition zones.

2. The roll-over protection structure of claim 1 wherein said spacedupright leg means includes at least one pair of substantially verticallegs spaced on either side of said operators station and having inwardlycurved upper end portions disposed in spaced facing relation, and anupper canopy supporting beam rigidly interconnecting said upper endportions of said legs above and in shielding relation to said operatorsstation.

3. The roll-over protection structure of claim 2 including a canopyhaving rolled side edges secured in overlapping relation to said upperend portions of said legs and to said upper beam and extended outwardlytherefrom in overhanging protecting relation with respect to saidoperators station.

4. The roll-over protection structure of claim 2 wherein said legs areof fabricated box-section configuration constructed of welds extendinggenerally longitudinally of said legs throughout the entire length oftheir respective transition zones and central portions.

necting relation to said lower end portions of said legs. i t *8

1. A roll-over protection structure comprising; a vehicle frame havingan operator''s station thereon, spaced upright leg means securable tosaid frame in upstanding relation from said operator''s station andhaving relatively rigid upper and lower end portions, and a deformablecentral portion providing a pair of elevationally spaced upper and lowertransition zones of substantially reduced cross sectional area from saidupper and loweR end portions with said zones being respectively disposedbetween said upper end portion and said central portion, and betweensaid lower end portion and said central portion so that when subjectedto loading during a vehicle roll-over the central portion is effectiveto absorb energy and predictably deform in locations spaced apredetermined distance from said upper and lower end portions of saidleg means and generally contiguously associated with said upper andlower transition zones.
 2. The roll-over protection structure of claim 1wherein said spaced upright leg means includes at least one pair ofsubstantially vertical legs spaced on either side of said operator''sstation and having inwardly curved upper end portions disposed in spacedfacing relation, and an upper canopy supporting beam rigidlyinterconnecting said upper end portions of said legs above and inshielding relation to said operator''s station.
 3. The roll-overprotection structure of claim 2 including a canopy having rolled sideedges secured in overlapping relation to said upper end portions of saidlegs and to said upper beam and extended outwardly therefrom inoverhanging protecting relation with respect to said operator''sstation.
 4. The roll-over protection structure of claim 2 wherein saidlegs are of fabricated box-section configuration constructed of weldsextending generally longitudinally of said legs throughout the entirelength of their respective transition zones and central portions.
 5. Theroll-over protection structure of claim 4 wherein the legs at saidtransition zones longitudinally inwardly neck down from theirrespectively adjacent end portions in an arcuately contouredconfiguration to provide a narrower transverse width in their respectivecentral portions, and including a lower beam mounted on said vehicleframe in transversely disposed interconnecting relation to said lowerend portions of said legs.